• Journal of the Korean Society for Precision Engineering
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• v.15 no.1
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• pp.19-25
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• 1998

Remote fault diagnosis and maintenance system using general telecommunication network is necessary for an effective fault diagnosis and higher productivity of NC machine tools. In order to monitor machine tool condition and diagnose alarm states due to electrical and mechanical faults, a remote data communication system for monitoring of NC machine fault diagnosis and status is developed. The developed system consists of (1) remote communication module among NC's and host PC using PSTN. (2) 8 channels analog data sensing module, (3) digital I/O module for control or NC machine, (4) communication module between NC machine and remote data communication system via RS-232C, and (5) software man-machine interface. Diagnostic monitoring results generated through a successive type inference engine are displayed in user-friendly graphics. The validity and reliability of the developed system is verified to be a powerful commercial version on a vertical machining center through a series of experiments.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.509-513
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• 1996

The information technology of computers and computer tools have become so powerful that virtual enterprises are not just concepts any longer The virtual enterprises comprise distributed facilities and it is necessary to have a collaborative system among them. This paper proposes the modeling process of web-based collaborative system in the distributed manufacturing environment. It also presents the information infrastructure in order to communicate and to share the information more efficiently among the collaboration subsystem. The web-based collaborative system consists of four processes: 1) product design, 2) procurement of DB information, 3) query process, and 4) negotiation. The proposed web-based collaborative system will be implemented with network technologies.

• Progress in Superconductivity and Cryogenics
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• v.7 no.2
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• pp.44-46
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• 2005

A SMES can be a perfect alternative energy storage device to the chemical batteries which are needed by most of the renewable energy supply systems. The chemical battery storage system is so expensive to maintain and causes another environmental problem because they are not recyclable. But, SMES has semi-permanent lifetime and no environmental problems cause it only need coolants which is non flammable, clean and recyclable gas. In order to verify the feasibility of a SMES for the renewable electrical power supply system, electrical characteristics of a test SMES coil with the photovoltaic power system were analyzed in this paper. Simulation results show that we can charge 40 amps of current in test SMES coil using solar power system. The experimental verification will be performed just after development of the peak power tracking system for the solar system.

• Journal of the Korea Safety Management & Science
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• v.9 no.6
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• pp.137-146
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• 2007

The objective of this paper is to study the establishing system of truck collaboration and to reduce traffic cost for participating transportation enterprises. The system of truck collaboration can enhance the transport efficiency and to reduce traffic cost without new investment for trucks and equipments. The type of truck collaboration should be enumerated (1) the system of head and branch base (2) the system of central terminal (3) the system of separating collection and delivery for cargo (4) the system of cooperating cargo order and truck allocation. The efficiency of truck collaboration is possible to be realized for transportation enterprises, receiver and sender of cargo.

• Journal of the Korean Society of Systems Engineering
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• v.1 no.2
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• pp.34-42
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• 2005

Logistic Support Analysis(LSA) and Logistic Supportability Review must be carried out as soon as possible in development stage in order to minimize operation/maintenance cost that head the list of weapon cost and improve logistic supportability of the weapon system. And the result must be used for hardware designs to set up to be able to input to the system design and logistic support elements. Therefore Logistic Support Elements must be planed/developed/supplied with the main combat system concurrently and performance and logistic supportability of the comabat system had better be improved mutually. This report describes maintenance concept changes of weapon systems, fault diagnosis function and test equipment state on the domestic MBT(main battle tank). And then it presents application and intensification of itself fault diagnosis system for a domestic future MBT considering connection with IETM(Interactive Electronic Technical Manual) and TE(Test Equipment).

• Journal of the Korea Safety Management & Science
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• v.8 no.4
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• pp.181-193
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• 2006

The purpose of this thesis addresses a development of an expert system to support a decision making of the vender selection. The researches related to the vender selection problems have been studied and they provide 23 criteria to select proper venders. In this thesis, 8 criteria have been used to construct a knowledge base of the expert system. The system in this thesis consists of 6 steps in its procedure. Step 1 decides a specification that satisfies customer's needs and Step 2 chooses a part supplied by a vender. The type of an outside order is decided in Step 3 and some venders satisfying the customer's needs are selected in Step 4. Some of the venders chosen from step 4 which do not satisfy the fatal cirteria(that is Quality, Delivery, Price) can be deleted in Step 5. In the last step, 8 cirteria is used to select 3 venders according to their ranking. Consequently, this program provides for a man, who does not have the experiances, an efficient way to select appropriate venders in the vender selection problems.

• Journal of Power Electronics
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• v.2 no.1
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• pp.11-18
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• 2002

The development of the solar and the wind energy is necessary since the future alternative energies that have no pollution and no limitation are restricted. Currently MW Class power generation system has been developed, but it still has a few faults with the weather condition. In order to solve these existing problems, combined generation system of photovoltaic and wind power was suggested. It combines wind power energy and solar energy to have the supporting effect from each other. However, since even combined generation system cannot always generate stable output with everchanging weather condition, power storage apparatus that uses elastic energy of spiral spring to combined generation system was also added for the present study.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.33 no.2
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• pp.127-132
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• 2010

Recently, the importance of quality control on the online collaboration system is increasing, since it is realized that many participants do not guarantee the quality of online collaboration's output anymore. Hence in this paper, we propose the framework of quality control in order to assure the quality of output from online collaboration system. The proposed framework provides the solution strategies to overcome the challenges of current collaboration systems. To do that, first of all we define the basic process (create, initiate, discuss, complete) of the online collaboration system based on wiki-based system or open source project, and then we find the challenges in each online collaboration process, and propose the effective strategy to overcome these challenges with reference cases including Wikipedia, OSS project, etc.

• Journal of the Korea Safety Management & Science
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• v.12 no.2
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• pp.65-73
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• 2010

In an automated industry PLC plays a central role to control the manufacturing system. Therefore, fault free operation of PLC controlled manufacturing system is essential in order to maximize a firm's productivity. On the contrary, distributed nature of manufacturing system and growing complexity of the PLC programs presented a challenging task of designing a rapid fault finding system for an uninterrupted process operation. Hence, designing an intelligent monitoring, and diagnosis system is needed for smooth functioning of the operation process. In this paper, we propose a method to continuously acquire a stream of PLC signal data from the normal operational PLC-based manufacturing system and to generate diagnosis model from the observed PLC signal data. Consequently, the generated diagnosis model is used for distinguish the possible abnormalities of manufacturing system. To verify the proposed method, we provided a suitable case study of an assembly line.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.8
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• pp.1130-1139
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• 2012

This paper proposes a LED lighting system using integrated power system composed of bridgeless PFC, LLC DC-DC transformer, and dimmable constant current LED driver module. The proposed LED lighting system features high efficiency, high power factor, and dimming capability. In order to verify the validity of the proposed system, the 2kW prototype system was built and tested. From the experimental results, it was confirmed that the maximun efficiency of 92.6% and maximum power factor of 99.7% can be achieved.